Two metal rods $1$ and $2$ of same lengths have same temperature difference between their ends. Their thermal conductivities are $K_1$ and $K_2$ and cross sectional areas $A_1$ and $A_2$ , respectively. If the rate of heat conduction in $1$ is four times that in $2$, then
Two metal rods $1$ and $2$ of same lengths have same temperature difference between their ends. Their thermal conductivities are $K_1$ and $K_2$ and cross sectional areas $A_1$ and $A_2$ , respectively. If the rate of heat conduction in $1$ is four times that in $2$, then
- A
$k_1\,\,A_2=4k_2\,\,A_1$
- B
$k_1\,\,A_1=4k_2\,\,A_2$
- C
$k_1=4k_2$
- D
$k_1\,\,A_1^2=4k_2\,\,A_2^2$
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